This invention relates in general to a method for installing a driveshaft assembly within a vehicle so as to transfer rotational power from an engine to an axle assembly. In particular, this invention relates to a method for pre-positioning the components of an axially adjustable driveshaft assembly prior to installation within such a vehicle to facilitate the installation process.
In most land vehicles in use today, a driveshaft assembly is provided for transmitting rotational power from an output shaft of an engine/transmission assembly to an input shaft of an axle assembly so as to rotatably drive one or more wheels of the vehicle. A basic vehicular driveshaft assembly includes a hollow cylindrical driveshaft tube and a pair of universal joints. A first one of the universal joints is connected between the output shaft of the engine/transmission assembly and a first end of the driveshaft tube, while a second one of the universal joints is connected between a second end of the driveshaft tube and the input shaft of the axle assembly. The universal joints provide a rotational driving connection from the output shaft of the engine/transmission assembly through the driveshaft tube to the input shaft of the axle assembly, while accommodating a limited amount of angular misalignment between the rotational axes of these three shafts.
In some instances, the driveshaft assembly must also accommodate a limited amount of relative axial movement between the engine/transmission assembly and the axle assembly. To accomplish this, it is known to divide the driveshaft tube into two separate driveshaft sections and provide an axially adjustable connection therebetween. Typically, the axially adjustable connection is embodied as mating male and female splined members provided on the two driveshaft sections. The male and female splined members cooperate to provide a rotational driving connection between the engine/transmission assembly and the axle assembly, while allowing a limited amount of relative axial movement therebetween. The splined connection between the two driveshaft sections is typically covered by an exterior seal, such as a flexible convoluted boot, which extends thereabout to prevent the entry of dirt, water, and other contamination. The splined connection may also have an interior sealing structure, such as a plug, for preventing contaminants from entering through the hollow yokes or driveshaft sections into the region of the splined members.
Typically, the driveshaft assembly is manufactured in one location, then shipped to another location for assembly into the vehicle. During assembly into the vehicle, the driveshaft assembly is initially positioned within the vehicle. Then, the ends of the driveshaft assembly are secured to the engine/transmission assembly and the axle assembly. When the driveshaft assembly being installed is axially adjustable, it is necessary to extend or retract the two driveshaft sections such that the overall length of the driveshaft assembly is approximately equal to the length between the engine/transmission assembly and the axle assembly. This extension and retraction of the driveshaft assembly is usually performed manually. In the past, the installer initially positioned the driveshaft assembly within the vehicle, then manually extended or retracted the components thereof to the desired length. It has been found that this manual extension and retraction is awkward to perform when the driveshaft assembly has been positioned within the vehicle. Furthermore, because of close manufacturing tolerances, a vacuum effect may render the manual extension and retraction of the driveshaft sections even more difficult when the driveshaft assembly is positioned within the vehicle. Inasmuch as the splined connection between the two driveshaft sections is covered by the flexible boot as described above, it has not been feasible to pre-adjust the overall length of the driveshaft assembly prior to installation within the vehicle. Thus, it would be desirable to provide a method for pre-positioning the driveshaft sections of an axially adjustable driveshaft assembly prior to installation within such a vehicle to facilitate the installation process.